Russia's foreign ministry building in central Moscow – home of a very busy Twitter account. Photograph: Boris Yelenin/AFP/Getty Images

There was a time when Soviet officials would plant stories in their pliant press or concoct honeytraps to bring down an out-of-favour diplomat. These days, the Russian state heads straight to Twitter.

Late on Monday night, the Russian foreign ministry launched an unprecedented attack on Michael McFaul, the US ambassador to Moscow, unleashing nine tweets in the space of an hour.

"The foreign ministry is utterly shocked at U.S. Aambassador Michael McFaul's remarks during a speech to students at the HSE," the onslaught began, referring to a speech last week on US-Russia relations to Moscow's higher school of economics.

"Ambassadors' job, as we understand it, is to improve bilateral ties, not to spread blatant falsehoods through the mediasphere," the foreign ministry account said.

By this point, it seems, McFaul had had enough. He took to Twitter to reply that his university talk had "highlighted over 20 positive results of 'reset,' that our governments worked together to achieve.". He later released slides from the talk, which focused on improvements in US-Russia relations.

McFaul was hounded by a Kremlin youth group immediately upon arriving in Moscow as ambassador earlier this year. State media have accused McFaul, a former professor who has written books on democracy, of being the hidden force behind opposition protests in Moscow this year.

The unfolding spectacle drew international attention. Carl Bildt, the Swedish foreign minister, took to his Twitter account to write: "I see that Russia MFA has launched a twitter-war against US Ambassador @McFaul. That's the new world – followers instead of nukes. Better."